Rate matching method in mobile communication system

ABSTRACT

A rate matching method is provided for a mobile communication system that performs an adjustment to a code rate based on an optimal level by puncturing or repetition to respective bit streams of transport channels. The rate matching method is preferably applicable to uplink and downlink rate matching for channel coding including turbo coding, convolutional coding and the like. The rate matching method for uplink can include executing coding for bits of a transport channel, and branching off the bits into a plurality of sequences, constructing a first interleaving pattern for the plurality of sequences, constructing a virtual interleaving pattern for at least one sequence based on a mapping rule with a corresponding first interleaving pattern and calculating different bit shifting values in each column of each virtual interleaving pattern. Then, a bit position to be punctured is determined in each constructed virtual interleaving pattern using the calculated bit shifting values.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 11/404,175,filed on Apr. 13, 2006, now U.S. Pat. No. 7,523,383, which is acontinuation of application Ser. No. 10/622,781, filed on Jul. 21, 2003,now U.S. Pat. No. 7,089,480, which is a continuation of application Ser.No. 09/615,603, filed on Jul. 13, 2000, now U.S. Pat. No. 6,622,281,which pursuant to 35 U.S.C. §119(a), claims the benefit of earlierfiling date and right of priority to Korean Application Nos. 28358/1999,filed Jul. 14, 1999, 48001/1999, filed on Nov. 1, 1999, 43254/1999,filed on Oct. 7, 1999 and 35023/1999, filed on Aug. 23, 1999, thecontents of all of which are hereby incorporated by reference herein intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the next generation mobilecommunications, and more particularly, to a rate matching method for thenext generation mobile communication system.

2. Background of the Related Art

The ARIB of Japan, ETSI of Europe, T1 of U.S.A., TTA of Korea and TTC ofJapan mapped out a more advanced next generation mobile communicationsystem based on a radio access technique and a core network technique ofthe existing global system for mobile communications (GSM) that servicesmultimedia such as sound, an image and data. The parties agreed withjoint researches to present a technical specification for the advancednext generation mobile communication system, and the project was calleda third generation partnership project (hereafter “3GPP”).

The 3GPP is classified into several technical specification groups(TSG). In a research field for a radio access network (RAN) among theTSGs of the 3GPP, a technical specification for an uplink rate matchingand a downlink rate matching is provided. The rate matching is realizedby adjusting to a code rate level most appropriate to a radio interfacethrough a puncturing process for removing a specific bit or a repetitionprocess for adding a specific bit for a bit stream provided via achannel coding.

Algorithms used in the rate matching can be divided into puncturingalgorithms and repetition algorithms. Further, different rate matchingalgorithms are embodied in an uplink and a downlink, which is the reasonwhy an interleaving for a rate matched bit stream is performed in thedownlink and a rate matching for an interleaved bit stream is executedin the uplink.

FIG. 1 is a block diagram showing the structure for an uplink in aconventional 3GPP standard. In the uplink, data streams of severaltransport blocks having the same quality of service (hereafter “QoS”)have a channel coding execution according to a desired code rate, andthen, are branched off into several sequences. These sequences arepassed through a procedure of a 1st interleaving in a unit of a codesymbol. Such 1st interleaved sequences undergo the rate matching usingthe puncturing algorithm or the repetition algorithm.

FIG. 2 represents a block diagram showing the structure for a downlinkin the conventional 3GPP standard. In the downlink, data streams ofseveral transport blocks having the same as ‘QoS’ have a channel codingexecution according to a required code rate, and then, are branched offinto several sequences. The sequences of the respective branches undergorate matching using the puncturing algorithm or the repetitionalgorithm. Such rate matched sequences have an execution of a 1stinterleaving in a unit of a code symbol.

In the channel coding applicable to the transport channel (TrCH) of theuplink or downlink there is a convolutional coding and a turbo coding.However, other specific channel coding may be applied thereto.

A multi-stage interleaver (MIL) is used as an interleaver for performingthe 1st interleaving in this uplink or downlink. For reference, the spanof the 1st interleaving using the MIL is same as a transmission timeinterval (TTL) of the TrCH.

The MIL writes a bit stream on an interleaver memory in a unit of a row,reads it in a unit of a column, and constructs an output bit stream. Atthis time, it is characterized that a rule based on a bit reversingorder is applied in an order of reading the interleaver memory.

For example, if the number of column for the 1st interleaver is 8, eachcolumn number can be represented with 3 digits. Bit reversing for thecolumn number can be performed in such a way that the column number bitvalue is reversed, namely, in such a method as ‘0(000)->0(000)’,‘1(001)->4(100)’, ‘2(010)->2(010)’, ‘3(011)->6(110) etc. and thereby thecolumn bit stream based on an order of “0 4 2 6 1 5 3 7” is outputted by1st MIL interleaver, instead of an output of the column bit stream basedon an order of “0 1 2 3 4 5 6 7”.

The following table 1 represents the order of the column bit streamoutputted from the MIL on the basis of respective columns of theinterleaver.

TABLE 1 R(k) K R(0) R(1) R(2) R(3) R(4) R(5) R(6) R(7) 2 0 1 4 0 2 1 3 80 4 2 6 1 5 3 7Table 1 shows bit reversing when the number of columns (k) of theinterleaver is 2, 4 and 8, respectively, and where R(k) indicates aresult of a bit reversing.

FIG. 3 provides an order of the column bit stream outputted from the MILin case that the column number of the interleaver, K, is 8 as shown inTable 1, in an example. Digits represented in shadow blocks of FIG. 3indicate the order of the column bit stream actually outputted from theinterleaver.

One code symbol in a turbo coder is constructed with a systematic bit, a1st parity bit and a 2nd parity bit. The first parity bit representsoutput bits of an upper Recursive Systematic Convolutional Coder (RSCcoder), and the second parity bit indicates output bits of a lower RSCcoder. In contrast to the convolutional code, in the turbo code animportance of the three bits constructing the code symbol is differentamong one another.

In other words, among the systematic sequence, the 1st parity sequenceand the 2nd parity sequence turbo-coded and branched off, the systematicsequence is relatively important and the remaining parity sequencesdecrease in importance, when decoding. Therefore, a method is needed forexcluding the puncturing for the systematic sequence and puncturingmutually equally only for the remaining parity sequences, in thepuncturing technique for the turbo code.

A conventional puncturing algorithm for the turbo code in the downlinkis described in the following. For the turbo code in the downlink, thepuncturing is generated in a unit of a code symbol, differently from theconvolutional code basically generating the puncturing in a unit of acode bit.

One example out of the puncturing algorithms for the turbo code in thedownlink provides that a puncturing position of the code symbol unit isdecided so as to constantly perform the puncturing in the code symbolunit, and after that, the parity sequences on a corresponding codesymbol position are alternately punctured. In another puncturingalgorithm for the turbo code in the downlink, a position having thepuncturing occurring in the code symbol unit is extended by twicedistance, and after that, the parity sequences are simultaneouslypunctured every a code symbol in which each puncturing occurs.

Such puncturing algorithms for the turbo code are considered in thedownlink. Since the puncturing procedures for the turbo code of thedownlink occurs before the interleaving, the puncturing can be performedindependently from the interleaving procedure.

However, if the puncturing algorithm for the turbo code are consideredin the uplink, the puncturing procedure for the rate matching should beperformed after the interleaving. Thus, additional terms need to beconsidered in comparison with the downlink.

As described above, the related art uplinks and downlinks in the 3GPPstandard have various disadvantages. That is, parameters used in thepuncturing procedure for the turbo code in the downlink cannot be usedas is, and other and/or additional parameters should be used to satisfya uniform puncturing of a code bit unit having a consideration for theinterleaving. In other words, for a uniform amount for the respectiveinterleaved column bit stream to be punctured, parameters are needed sothat the puncturing may be uniformly generated even for the bit streambefore the interleaving.

However, it is the present situation such a puncturing technique forsuch turbo code of the uplink is not yet considered and needed. Further,when the parameter used in the existing downlink is used in the uplinkwithout change, even in the repetition procedure for the turbo code, aproblem is caused that only a stream of a specific row is repeated.Also, it is the present situation that a rate matching method is neededthat is applicable to all of a channel code such as the turbo code andthe convolutional code etc. and channel codes used in the uplink anddownlink.

The above references are incorporated by reference herein whereappropriate for appropriate teachings of additional or alternativedetails, features and/or technical background.

SUMMARY OF THE INVENTION

An object of the present invention is to solve at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed hereinafter.

Another object of the present invention is to provide a rate matchingmethod of a mobile communication system that substantially obviate oneor more of the limitations and disadvantages of the related art.

Another object of the present invention is to provide an improved ratematching method of providing a uniform puncturing pattern and a uniformrepetition pattern for each bit stream of TrCHs supplying mutuallydifferent services in the next generation mobile communication systemusing a Wideband Code Division Multiple Access (hereafter “W-CDMA”)method.

In order to achieve at least the above-described objects of the presentinvention in a whole or in parts, there is provided a rate matchingpuncturing method in a mobile communication system that includes (a)performing a channel coding for bits of a transport channel andoutputting one or more channel-coded sequences, (b) constructing a firstinterleaving pattern based on a unit of a symbol for each of thechannel-coded sequences, (c) constructing virtual interleaving patternsfor said each of the channel-coded sequences by considering a mappingrule with a corresponding first interleaving pattern,

(d) calculating different bit shifting values in each column of theconstructed virtual interleaving patterns and determining a bit positionto be punctured, and (e) puncturing bits in each first interleavingpattern constructed in (c), based upon (d).

To further achieve at least the above-described objects of the presentinvention in a whole or in parts, there is provided a rate matchingmethod for uplink in a mobile communication system that includesexecuting in a frame unit a turbo coding for bits of a transportchannel, and branching off the bits into a systematic sequence, a firstparity sequence and a second parity sequence, constructing a firstinterleaving pattern based on a unit of a symbol for the branched-offsequences, constructing a virtual interleaving pattern for each paritysequence turbo-coded by considering a mapping rule with a correspondingfirst interleaving pattern, calculating different bit shifting values ineach column of each virtual interleaving pattern, deciding a bitposition to be punctured in each constructed virtual interleavingpattern by using the calculated bit shifting values, and puncturing bitsaccording to the decided bit position to be punctured.

To further achieve at least the above-described objects of the presentinvention in a whole or in parts, there is provided a sequencerepetition method for an uplink rate matching, in a mobile communicationsystem including performing in a frame unit a channel coding for bits ofa transport channel, constructing a first interleaving pattern based ona unit of a symbol, calculating a mean repetition distance according toa prescribed bit repetition rate using a mapping rule with theconstructed first interleaving pattern, computing different bit shiftingvalues based on respective columns in the constructed first interleavingpattern by using the mean repetition distance, and deciding a repetitionbit position in the constructed first interleaving pattern by using acorresponding bit shifting value.

To further achieve at least the above-described objects of the presentinvention in a whole or in parts, there is provided

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objects and advantages of the invention may be realizedand attained as particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in detail with reference to thefollowing drawings in which like reference numerals refer to likeelements wherein:

FIG. 1 represents a block diagram showing a portion of structure for arelated art transport channel multiplexing an uplink according to a 3GPPstandard;

FIG. 2 represents a block diagram showing a portion of structure for arelated art transport channel multiplexing a downlink according to a3GPP standard;

FIG. 3 illustrates an exemplary order of a column bit stream outputtedfrom a MIL when the column number of an interleaver is ‘K=8’;

FIG. 4 is a block diagram showing a preferred embodiment of an uplinkrate matching procedure in accordance with the present invention;

FIG. 5 depicts a block diagram providing construction of an exemplarychannel encoder of FIG. 4;

FIG. 6 sets forth an interleaving pattern of an MIL in case that thecolumn number of a used interleaver is ‘K=8’;

FIGS. 7 a-7 b are diagrams that show an exemplary virtual interleavingpattern for two coded parity sequences;

FIGS. 8 a-8 f show puncturing patterns generated by another preferredembodiment of an uplink rate matching procedure according to the presentinvention concerning of the virtual interleaving patterns shown in FIGS.7 a-7 b;

FIGS. 9 a-9 c are diagrams that show exemplary puncturing patterns ofvirtual interleavers applied to a 1st interleaving pattern;

FIGS. 10 a-10 c are diagrams that show puncturing patterns generated byanother preferred embodiment of an uplink rate matching procedureaccording to the present invention of the virtual interleaving patternshown in FIG. 7 when the quantity of puncturing per column of a 1stinterleaver is an odd number;

FIGS. 11 a-11 c are diagrams that show puncturing patterns generated byanother preferred embodiment of an uplink rate matching procedure inaccordance with the present invention when a quantity of puncturing percolumn of a 1st interleaver is an odd number;

FIG. 12 is a diagram that shows another puncturing pattern generated byanother preferred embodiment of a rate matching procedure based on anoptimal level applied to a 1st interleaving pattern when a quantity ofpuncturing per column of a 1st interleaver is an odd number;

FIGS. 13 a-13 b are diagrams that show a puncturing pattern for a turbocode provided by controlling a parameter ‘a’ according to a preferredembodiment of the rate matching procedure based on an optimal level ofthe present invention;

FIGS. 14 a-14 b are diagrams showing puncturing patterns on a virtualinterleaver through two various shifting parameter calculations when anoverall puncturing more than 33.3% is generated, namely, in case apuncturing over 50% for each parity sequence is generated; and

FIGS. 15 a-15 b are diagrams that show a repetition pattern.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Initially, two decoders that are used in a system utilizing a turbo codewill be described. Two decoders are positioned on both ends of aninterleaver in turbo decoder, and code bits inputted to first and seconddecoders are respectively provided with elements of a 1st paritysequence and a 2nd parity sequence. In order to improve an overallperformance of the turbo decoder, it is important that two decoders eachhave an equal decoding capability. In an aspect of one decoder, also, itis important in increasing or maximizing a performance of the decoderthat a puncturing on an input parity sequence of the decoder occurs by auniform interval.

Therefore, it is very important that the puncturing based on the uniformquantity should influence upon the 1st parity sequence of an upper RSCand the 2nd parity sequence of a lower RSC by considering suchcharacteristic of the decoding procedure in a transmitting side, and thepuncturing based on a uniform interval should influence upon therespective parity sequences.

Accordingly, a preferred embodiment of a puncturing method for a turbocode of an uplink according to the present invention preferablysatisfies the following conditions. First, a puncturing for a systematicsequence element is excluded. Second, for parity sequence elements, thepuncturing based on the uniform quantity is generated from elements ofthe first and second parity sequences. Third, in an overall bit columnbefore a 1st interleaving is performed in a unit of a code symbol, aposition of the puncturing on each parity sequence has a uniforminterval.

In addition to these three conditions, one additional condition shouldbe considered, namely, a specific characteristic of an uplink. Thus, apuncturing by the same quantity is generated for all radio frames passedthrough the interleaving. That is, a uniform code bit for respectiveinterleaved column bit streams is punctured.

In the preferred embodiments according to present invention, puncturingthe turbo code provided in the uplink satisfies the above conditions.

Preferred embodiments of the puncturing procedure for a turbo code ratematching of an uplink will now be described in accordance with thepresent invention. For convenience, a case that the number of columns,K, in an interleaver is ‘8’ will now be described. The present inventionis, of course, not intended to be so limited and is applicable to othercases such as when the number of columns, K, in the interleaver is 1, 2,4.

FIG. 4 sets forth a block diagram showing a first preferred embodimentof an uplink rate matching procedure based on an optimal level inaccordance with the present invention. FIG. 5 provides a block diagramshowing additional detail of a channel encoder that can be used in FIG.4.

In a case of ⅓ rate turbo coding, x is an output of a channel encoder 10is a systematic sequence, y is a 1st parity sequence, and z is a 2ndparity sequence generated in the lower RSC encoder through an input of aturbo-interleaved systematic sequence. These branched-off sequences areprovided as outputs in the turbo coding result for the TrCH, and arethen passed through the 1st interleaving, where the 1st interleaving ispreferably performed for one sequence obtained by multiplexing thebranched-off sequences.

Two parity sequences y,z among the turbo-coded outputs are outputs ofrespective RSC coders 12,13.

In particular, each independent virtual interleaving pattern isconstructed for a 1st parity sequence (y) element and a 2nd paritysequence (z) element among three sequences passed through the 1stinterleaving. Preferably, the construction is performed in a bitselection block 30. A rate matching block (RMB) 40 can separately applythe same puncturing process or algorithm to two individual virtualinterleaving patterns constructed in the bit selection block 30.

FIG. 6 indicates an interleaving pattern of a 1st interleaver 20 whenthe column number, K, of the interleaver used in the first preferredembodiment is 8, and FIGS. 7 a-7 b depict virtual interleaving patternsfor two coded parity sequences. In particular, FIG. 7 a shows a virtualinterleaving pattern for the 1st parity sequence element, and FIG. 7 bpresents a virtual interleaving pattern for the 2nd parity sequenceelement.

In FIG. 7, digits provided on the upper shadow portions represent columnnumbers on an original 1st interleaver of FIG. 6. In other words, itshows a relation between column numbers on the virtual interleaver andcolumn numbers on the actual 1st interleaver.

The rate matching block (RMB) 40 in the first preferred embodiment of apuncturing process for a turbo code of an uplink basically uses thefollowing two procedures so that the puncturing based on each uniformquantity in two virtual interleavers with such construction may begenerated by a uniform interval on a sequence before the virtualinterleaving. First, shifting parameters per column of each virtualinterleaving pattern are calculated. Second, the first calculatedshifting parameter per column is applied to an actual puncturingalgorithm for an original interleaving pattern. That is, the shiftingparameters per each column of the virtual interleaving pattern arecomputed, and this is mapped to the shifting parameter for each columnof the 1st interleaving pattern.

The RMB 40 is used in a process in which the puncturing is performed bythe P number of bits every individual column sequence having a bitlength of N_(C) in the 1st interleaving pattern shown in FIG. 6. Thus,for the 1st parity sequence element having a bit length of an N_(C)/3 inevery respective column, the puncturing is performed by the P/2 numberof bits. For the 2nd parity sequence element having the bit length ofthe N_(C)/3 in every respective column, the puncturing is also performedby the P/2 number of bits.

At this time, as described above, the RMB 40 separately applies the samepuncturing process to two respective virtual interleaving patternsconstructed in the bit selection block 30, namely, to the respectiveparity sequence elements. For that, first, an initial error offset valuee_(ini) should be gained for each column of the 1st interleaver 20. Inorder to gain the initial error offset value e_(ini), the shiftingparameter to be applied to each column of an interleaver memory shouldbe calculated respectively by a first parameter determination method oralgorithm and a second parameter determination method or algorithm.

The first parameter determination algorithm and the second parameterdetermination algorithm for calculating shifting parameters S1,S2 to beused in the puncturing algorithm for the first and second paritysequence elements will now be described.

In the first parameter determination process for computing the shiftingparameter S1 for the first parity sequence element, when each column inthe 1st interleaver is constructed by the bit length of N_(C) as shownin FIG. 6 and the puncturing by the P number of bits is performed inevery respective column, the following preconditions are required. Inthe following described procedures, it is first assumed for anexplanatory convenience that P has only a value of an even number. Ageneration for a P value of an odd number will be described later.

First, a number of code symbol N=└N_(C)/3┘: herewith, a character └x┘indicates the maximum integer value that is not over x, which means acut-off under a decimal point of x. N is not an actual code symbol butis regarded as the code symbol.

Second, the number of code symbols after the puncturing,N _(i) =N−P/2  (1)

Third, q=└N/|N_(i)−N|┘; wherein q represents an average puncturingdistance of the code symbol unit.

When q is calculated in the above preconditions, the first parameterdetermination algorithm for calculating the shifting parameter S1applicable to each column from the calculated q value is represented asfollows.

“if(q≦2) { for(k=0; k < K; k++) { if((k mod 2)==0) S₁[R[(3k+1)mod K]] =0 ; else S₁[R[(3k+1)mod K]] = 1 ; } } else { if(q is even)$q^{\prime} = {q - \frac{{GCD}\;\left( {q,K} \right)}{K}}$ else q′ = qfor(i=0; i<K; i++) { k = ┌i*q′┐mod K  ; S₁[R[(3k + 1)mod K]]=┌i*q′┐divK; } } ”

In the above first parameter determination algorithm,

$``{q^{\prime} = {q - \frac{{GCD}\left( {q,K} \right)}{K}}}"$is provided to prevent a consecutive puncturing in the same column,wherein “GCD(q,K)” indicates the greatest common divisor, and“R[(3k+1)mod K]” is the expression provided by considering a mappingfrom the virtual interleaving pattern to the actual first interleaverand a relation between the respective columns of the first interleaverand an order of radio frames.

“S₁[R[(3k+1)mod K]]=┌i*q′┐ div K” is the expression provided to computethe shifting parameter S1 per radio frame resultantly, where a character┌x┐ indicates the minimum integer value that is more than x.

In the second parameter determination process for computing the shiftingparameter S2 for the second parity sequence element, when each column ofthe 1st interleaver is constructed by the bit length of N_(C) as shownin FIG. 6 and the puncturing by the P number of bits is performed everyrespective column, the following preconditions are preferably required.

First, a code symbol N=└N_(C)/3┘: herewith, └x┘ is the maximum integervalue which is not over x, which means a cut-off under a decimal pointof x, and N is not an actual code symbol but is regarded as the codesymbol.

Second, the number of code symbols after the puncturing is,N _(i) =N−P/2  (2)Third, q=└N/|N_(i)−N|┘; wherein q represents an average puncturingdistance of the code symbol unit.

When q is calculated in the above preconditions, the second parameterdetermination algorithm for calculating the shifting parameter S2applicable to each column from the calculated q value is represented asfollows.

“if(q≦2) { for(k=0; k < K; k++) { if((k mod 2)==0) S₂[R[(3k+2)mod K]] =0 ; else S₂[R[(3k+2)mod K]] = 1 ; } } else { if(q is even)$q^{\prime} = {q - \frac{{GCD}\;\left( {q,K} \right)}{K}}$ else q′ = qfor(i=0; i<K; i++) { k = ┌i*q′┐mod K  ; S₂[R[(3k + 2)mod K]]=┌i*q′┐divK; } } ”

In the above second parameter determination algorithm,

$``{q^{\prime} = {q - \frac{{GCD}\left( {q,K} \right)}{K}}}"$is provided to prevent a consecutive puncturing in the same column,wherein “GCD(q,K)” indicates the greatest common divisor, and“R[(3k+2)mod K]” is the expression provided by considering a mappingfrom the virtual interleaving pattern to the first actual interleaverand a spatial relation between the respective columns of the firstinterleaves and an order of radio frames.

“S₂[R[(3k+2)mod K]]=┌i*q′┐ divK” is the expression provided to computethe shifting parameter S2 per radio frame resultantly, wherein thecharacter ┌x┐ indicates the minimum integer value more than x.

The shifting parameters S1,S2 are calculated for each column by suchabove parameter determination algorithms. Then, the following ratematching process or algorithm for the puncturing is performed by usingthe initial error offset value e_(ini) gained therefrom.

A computation procedure of the initial error offset value e_(ini) forthe first parity sequence element and a computation procedure of theinitial error offset value e_(ini) for the second parity sequenceelement are applied separately to the rate matching puncturingalgorithm. According to preferred embodiments of the present invention,the following rate matching puncturing algorithm preferably requiresfollowing basic preconditions.

First, N_(C): number of data bits in each column of the 1st interleaver.Second, P=maximum amount of puncturing allowed per each column in the1st interleaver.

Third, N=└N_(C)/3┘: determines the number of bits for each parity bitsequence and determines number of executions in the following loop.Fourth, the number of code symbols after the puncturing: N_(i) (1stparity sequence: the expression (1), 2nd parity sequence: the expression(2)). Fifth, k is the radio frame numbers of the first interleaver,{k=0, 1, 2, 3, . . . , K−1}, wherein K is the number of columns in thefirst interleaver.

“if the puncturing is to be performed y = (N − N_(i))   ; the number ofpuncturing bits   e_(ini) = (a*S_(j)(k)*y+N) mod (a*N) ; where j is 1for the 1st parity sequence and 2 for the 2nd parity sequence.  if(e_(ini)=0)  e_(ini) = a*N   e = e_(ini)   m = 1   ; index ofcurrent bit   do while m <= N     e = e − a*y  ; update error   if e <=0 then ;check if bit number m should be punctured       puncture m-thbit from each parity sequence     e = e+ a*N  ; update error  end if   m= m + 1   ; index of next bit end do”

Such above procedure is called as a pattern determination algorithm ofthe rate matching. Several puncturing patterns according to preferredembodiments can be obtained by providing differing values of ‘a’ in thepattern determination algorithm. For example, in a case of aconvolutional code, 2 is used as ‘a’ value. But, in a case of the turbocode, mutually different ‘a’ values for the first and second paritysequences can be used. In other words, ‘a=2’ can be used for the firstparity sequence and ‘a=1’ can be used for the second parity sequence.Alternatively, ‘a=1’ can be used for the first parity sequence and ‘a=2’can be used for the second parity sequence. Also, ‘a=2’ may be used forboth the first and second parity sequences.

FIGS. 8 a-8 f are diagrams that show puncturing patterns generated bythe first preferred embodiment of the inventive uplink rate matchingprocedure, concerning of the virtual interleaving pattern shown in FIGS.7 a-7 b. However, the present invention is not intended to be solimited. FIG. 8 a shows the puncturing pattern of the virtualinterleaver for the first parity sequence (y) element, and FIG. 8 bshows the puncturing pattern of the virtual interleaver for the secondparity sequence (z) element. In this example, it is supposed that anapplication to all of the first and second parity sequences is possibleby fixing the ‘a’ value as 2.

FIG. 8 c is a diagram that represents the puncturing pattern on thevirtual interleaver of the first parity sequence in case that the ‘a’value is as ‘1’. FIG. 8 d is a diagram that represents the puncturingpattern on the virtual interleaver of the second parity sequence in casethat the ‘a’ value is as ‘2’. FIG. 8 e is a diagram that provides thepuncturing pattern on the virtual interleaver of the second paritysequence in case that the ‘a’ value is as ‘2’. FIG. 8 f is a diagramthat shows the puncturing pattern on the virtual interleaver of thesecond parity sequence in case that the ‘a’ value is as ‘1’.

FIGS. 9 a-9 c are diagrams that show an overall puncturing pattern incase that the puncturing pattern of each virtual interleaver shown inFIGS. 8 a-8 f is actually applied to the first interleaving pattern.FIG. 9 a shows the puncturing pattern of a case of fixing the ‘a’ valueas ‘2’ and using it for the first and second parity sequences. FIG. 9 bis for the puncturing pattern of a case of using the ‘a’ value as eachof 1 and 2 for the first and second parity sequences. FIG. 9 c is thepuncturing pattern for a case that the ‘a’ value is used as each of 2and 1 for the first and second parity sequences.

FIGS. 9 a-9 c provide a case that the first interleaved whole bit numberis 288 and 32 bits among them are punctured. In the above preferredembodiments of the rate matching algorithm, 4 bits based on each columnof the first interleaving pattern are punctured. That is, 4 bits among32 bits (288/8) of each column are punctured.

In comparing such case with the virtual interleaving pattern for eachparity sequence elements as shown in FIGS. 7 a-7 b, respectively, twobits per each column are each punctured in each virtual interleavingpattern. In other words, 2 bits among 12 bits (96/8) of each column arepunctured.

The inventive rate matching puncturing procedure for the turbo code ofthe uplink according to the first preferred embodiment, which wasdescribed above, is preferably for the case that the puncturing occursso that a target code rate may become under ½, and is also for the casethat the puncturing bit number is an even number bit for each column ofthe first interleaver. However, the present invention is not intended tobe so limited. For example, an odd number bit can be punctured per eachcolumn for the first interleaved overall bit column. Accordingly, apreferred embodiment of a procedure for puncturing based on an optimallevel will now be described for cases that the target code rate is under½ and the puncturing bit number is the odd number bit in each column ofthe first interleaving pattern. FIGS. 10 a-10 c provide puncturingpatterns generated by uplink rate matching procedure concerning of thevirtual interleaving pattern shown in FIGS. 7 a-7 b in case that thequantity of puncturing per column of a 1st interleaver is an odd number.Different from in FIGS. 9 a-9 c where an even number bit is puncturedfor each column of the first interleaving pattern, FIG. 10 shows thecase that the odd number bit is punctured for each column of the firstinterleaved pattern.

Further in FIGS. 9 a-9 c, 32 bits for the first interleaved overall bitcolumn are punctured. Namely, 4 bits per each column are punctured.

However, 24 bits for the first interleaved overall bit column arepunctured in the preferred embodiment shown in FIGS. 10 a-10 c. Namely,3 bits per each column should be punctured.

Therefore, if performed using the above-described parameterdetermination algorithm, 1.5 bits should be punctured for each of thefirst and second parity sequence elements. But, since that is actuallyimpossible, complementary methods will now be described.

Solving such problems will now be described using three methodsaccording to preferred embodiments of the present invention. In a firstmethod, in case three bits for each column of the first interleavingpattern should be punctured, it is the method of puncturing two bits by┌1.5┐=2 on the first parity sequence and also puncturing one bit by└1.5┘=1 on the second parity sequence. In this case, the above-mentionedexpressions (1) and (2) should be preferably generalized as follows.

-   -   N_(i)=N−┌P/2┐(1′); 1st parity sequence, and    -   N_(i)=N−└P/2┘(2′); 2nd parity sequence.

In a second method, it is the method of embodying the parameterdetermination algorithm so that one bit is punctured by └1.5┘=1 on thefirst parity sequence and two bits are punctured by ┌1.5┐=2 on thesecond parity sequence. In this case, the above-described expressions(1) and (2) should be generalized as follows.

-   -   N_(i)=N−└P/2┘(1″); 1st parity sequence, and    -   N_(i)=N−┌P/2┐(2″); 2nd parity sequence.

In other words, in embodying the parameter determination algorithm, forthe remaining first and second parity sequences excepting of thesystematic sequence among sequences outputted after the turbo coding, incase a pre-decided puncturing bit number is P, the ┌P/2┐ number of bitsare punctured for the first parity sequence and the └P/2┘ number of bitsare punctured for the second parity sequence. Alternatively, the └P/2┘number of bits are punctured for the first parity sequence and the ┌P/2┐number of bits are punctured for the second parity sequence.

However, problems can occur when the shifting parameter is calculatedand the puncturing is performed by such method. That is, in case thatthe quantity of puncturing, P, is an odd number, if the └P/2┘ number ofpuncturing is performed on the first parity sequence and the ┌P/2┐number of puncturing is performed on the second parity sequence, thereexists a difference caused in the puncturing number by the number ofcolumns of the first interleaver in an overall aspect. In other words,if the number of columns of the first interleaver is K, the overallpuncturing quantity of the 1st parity sequence becomes a smallerquantity by K at maximum in comparison with the puncturing quantity ofthe 2nd parity sequence. That is, the puncturing on the first and secondsequences each has a uniform puncturing interval, but its puncturinginterval becomes mutually different on the 1st and 2nd parity sequences.In this example, the puncturing interval on the first parity sequencehas a larger value in comparison with the puncturing interval on thesecond parity sequence. However, the difference of the puncturingquantity by K at maximum does not significantly influence the wholeperformance of the turbo decoder.

FIGS. 10 a-10 b show resultant puncturing patterns when the number ofpunctures P is 3 for cases that the └P/2┘=1 number of puncturing isperformed on the first parity sequence and the ┌P/2┐=2 number ofpunctures are performed on the second parity sequence. Herewith, it isassumed that the ‘a’ value is applied as 2 for all of the first andsecond parity sequences. FIG. 10 a shows the puncturing pattern on thevirtual interleaver for the 1st parity sequence, and FIG. 10 b shows thepuncturing pattern on the virtual interleaver for the 2nd paritysequence. FIG. 10 c provides a resultant puncturing pattern on the 1stinterleaver.

FIGS. 11 a-11 b provide the resultant puncturing pattern when the numberof punctures P is 3 for cases that the ┌P/2┐=2 number of punctures areperformed on the first parity sequence and the └P/2┘=1 number ofpuncturing is performed on the second parity sequence. FIG. 11 a showsthe puncturing pattern on the virtual interleaver for the 1st paritysequence, and FIG. 11 b shows the puncturing pattern on the virtualinterleaver for the 2nd parity sequence. FIG. 11 c indicates a resultantpuncturing pattern on the 1st interleaver.

In the third method, when the quantity of punctures per column is P, abit shifting value on the virtual interleaver is calculated through thepuncturing quantity of ┌P/2┐. An initial error offset e_(ini) of eachRMB is computed by using such calculated bit shifting value S1 and S2.In each RMB, the rate matching puncturing is performed by using thiscomputed e_(ini) value so as to generate the puncturing of ┌P/2┐. Inthis case, the above-described expressions (1) and (2) can be expressedas follows.

-   -   N_(i)=N−┌P/2┐(1′″); 1st parity sequence, and    -   N_(i)=N−┌P/2┐(2′″); 2nd parity sequence.

After that, the rate matching pattern determination algorithm isexecuted so that the puncturing of a partial bit, which is 1 bit in thiscase, is excluded for the 1st or 2nd parity sequence. The quantity ofsuch executed overall puncturing should be P*K. In order to satisfy suchrequirements, several methods can be used. Describing an initial method,the puncturing for one bit on the first parity sequence is excluded, forcolumns in an order of the even number of the 1st interleaver. Meantime,in columns based on the order of an odd number, the puncturing for onebit on the second parity sequence is excluded. When such procedures arerepeated, on the even numbered columns of the interleaver, thepuncturing is increased by 1 bit on the second parity sequence relativeto the 1st parity sequence. On the odd numbered columns, the puncturingis more by 1 bit on the first parity sequence relative to the secondparity sequence. Further, an opposite method to this can be consideredaccording to the present invention. However, a new logic for excludingthe 1 bit puncturing per each interleaver column is needed. One methodfor this logic according to the preferred embodiments is to provide apuncturing position to be excluded (e.g., as a final puncturingposition) when the puncturing per each column is performed on eachparity sequence.

In an execution another preferred embodiment of the rate matchingalgorithm for the K/2 number of columns before the 1st interleavingpattern, a final puncturing on the 1st parity sequence is excluded, andfor the post K/2 number of columns, a final puncturing on the 2nd paritysequence is excluded. Again, the opposite case can also be used.

FIG. 12 is a diagram that shows the puncturing pattern for a case ofusing the above described third method, in performing the puncturing of3 bits per each column. That is, the method is used for that thepuncturing pattern of each virtual interleaver is gained by ┌P/2┐=2,after that, in an actual puncturing procedure the final puncturing ofthe 1st parity sequence is excluded in the even numbered columns and thefinal puncturing of the 2nd parity sequence is excluded in the oddnumbered columns.

In the above-described third method, the puncturing quantity on eachparity sequence preferably always has an equal value with each other,regardless of that the puncturing number P per each column of the 1stinterleaver is the odd number or the even number. But this method canhave a shortcoming. Thus, an additional logic is needed for excludingthe final puncturing of any parity sequence per column. Anothershortcoming is the puncturing requirement for a uniform interval on eachparity sequence is not satisfied. That is, since the final puncturing isexcluded according to a case of each column, it can be noted that auniformity in the puncturing interval is upset in an aspect of thesequence before an original interleaving, as shown in FIG. 12.

The above-mentioned three methods can settle a problem caused when thepuncturing number P per each column of the 1st interleaver is an oddnumber. Three methods all have the respective advantages, merits canhave shortcomings. But one of the above first and second methods may bemore preferable, considering a complication caused by an addition of alogic and a trade-off between performance.

In addition, the preferred embodiments were described above centering onthe uniform puncturing for the turbo code. However, the presentinvention is not intended to be so limited.

The above-described parameter determination process and the ratematching puncturing process are applicable even to a case that thechannel encoder performs the convolutional coding. For example,according to another preferred embodiment of the inventive rate matchingprocedure, the puncturing algorithm for the convolutional code of theexisting bit unit is used as it is, and also, the puncturing positionbased on a uniform interval on each parity sequence can be designated.Therefore, the uniform puncturing for the turbo code of the uplink isrealized.

A procedure for deciding an optimal parameter so as to get the uniformpuncturing pattern for a channel code such as the turbo code and theconvolutional code etc. on the basis of the above-described preferredembodiments of the rate matching puncturing algorithm will now bedescribed. Further, preferred embodiments of a rate matching puncturingprocedure applicable to all of the channel code used in the uplink andthe channel code used in the downlink will now be described.

Before additional inventive detailed description, the RMB in FIG. 4performs that algorithm by applying several sequences branched off, tothe following rate matching algorithm, according to a target code rate.The RMB can use several parameters. The parameters used according to thetarget code rate include a parameter representing the number of bits foreach branched off input sequence, a parameter indicating a bit quantitypunctured on each branched off bit stream passed through a channelcoding and a parameter used in adjusting a pattern of the puncturing,for example.

If the RMB has an input of the turbo-coded sequences, the puncturing forthe systematic sequence is excluded. Thus, a parameter valuerepresenting the puncturing bit quantity becomes ‘0’, and the parametervalue indicating the puncturing bit quantity for the first and secondparity sequences becomes respectively ┌P/2┐ or └P/2┘.

In the above-described preferred embodiments of rate matching algorithmfor the turbo code of the uplink, parameters as shown in table 2 can beused to get the uniform puncturing pattern or a uniform repetitionpattern. As shown in table 2, an available combination totals six. Inother words, it is available to gain six mutually different puncturingpatterns by changing the ‘a’ values and the puncturing quantity for theindividual parity sequence.

TABLE 2 systematic 1st parity 2nd parity sequence (x) sequence (y)sequence (z) a 2 2 2 2 1 2 2 1 1 number of 0 ┌P/2┐ or └P/2┘ ┌P/2┐ or└P/2┘ puncturing bits sequence length └N_(c)/3┘ └N_(c)/3┘ └N_(c)/3┘

Even though any one out of the above six combinations is used in theuplink, there is not a large difference in an overall performance of theturbo decoder. But, the preferred embodiments of the rate matchingpuncturing process can be applied not only to the uplink but also to thedownlink by properly controlling the parameter ‘a’ for adjusting thepunctured bit position and also is applicable to the convolutional code.For that, preferred embodiments of a RMB can preferably use parametersrepresented in the following tables 3, 4 and 5.

TABLE 3 systematic 1st parity 2nd parity sequence (x) sequence (y)sequence (z) a 2 1 2 number of 0 └P/2┘ ┌P/2┐ puncturing bits sequencelength └N_(c)/3┘ └N_(c)/3┘ └N_(c)/3┘

Table 3 shows parameters preferably used in an inventive RB for theturbo code according to the present invention. In an example, in casethat ‘a’ is fixed as 2 on all two parity sequences and then it isapplied to the rate matching algorithm, a deduction by 2*y from theinitial error offset value e_(ini) is consecutively performed. Then, acorresponding bit is punctured when its updated error value satisfies acondition of “e≦0”. After the puncturing, 2*N is added to a finalupdated error value and the algorithm can preferably operatecontinuously to determine a bit to be next punctured.

However, when applying parameters of table 3, a bit position initiallypunctured on the first parity sequence is increased by about twice. If amean puncturing distance is represented in an integer number, it isincreased exactly by twice, which is shown in FIG. 11.

FIG. 13 a depicts the puncturing patterns for the turbo code in casethat the parameter ‘a’ used in the inventive optimal rate matchingpuncturing procedure is used as 2 in all two parity sequences. FIG. 13 billustrates the puncturing patterns for the turbo code in case that theparameter ‘a’ used in the inventive optimal rate matching procedure isused as 1 for the 1st parity sequence and is used 2 for the 2nd paritysequence.

As known in FIGS. 13 a and 13 b, the parameter ‘a’ for adjusting thepuncturing bit position has an application of 1 for the 1st paritysequence and has an application of 2 for the 2nd parity sequence.Therefore, the uniform puncturing for the 1st and 2nd parity sequencesis ensured through the same puncturing algorithm. Of course, the uniformpuncturing is satisfied even for the whole parity sequence pair, whichis a ½ rate puncturing pattern that is known as Berrou. That is to say,when the parameters shown in table 3 is used, the puncturing pattern ofBerrou can be embodied through the rate matching puncturing procedure.

Tables 4 and 5 show parameters usable in the RMB for the convolutionalcode.

TABLE 4 557₈ 663₈ 711₈ sequence (x) sequence (y) sequence (z) a 2 1 2number of puncturing P 0 0 bits sequence length └N_(c)/3┘ └N_(c)/3┘└N_(c)/3┘

TABLE 5 557₈ 663₈ 711₈ sequence (x) sequence (y) sequence (z) a 2 1 2number of puncturing ┌P/2┐ └P/2┘ 0 bits sequence length └N_(c)/3┘└N_(c)/3┘ └N_(c)/3┘For ⅓ rate convolutional code being currently used in 3GPP standard, achannel encoder uses “557₈=101101111₂”, “663₈=110110011₂”, and“711₈=111001001₂” polynomials.

Preferably, the sequence outputted by the “557₈=101101111₂” polynomialis ‘x’, the sequence outputted by “663₈=110110011₂” polynomial is ‘y’,and the sequence outputted by “711₈=111001001₂” polynomial is ‘z’. In apreferred embodiment of a rate matching algorithm for the convolutionalcode, uniform puncturing for the channel-coded overall bit stream isperformed. This is based on the condition that all the respective outputsequences have the same importance in a case of executing theconvolutional coding. In contrast, the systematic sequence among theoutput sequences of the channel encoder has a higher importance incomparison with the first and second parity sequences when the channelencoder performs the turbo coding.

However, even when the channel encoder actually performs theconvolutional coding, each output sequence has different influences uponan overall hamming weight. Consequently, in order for a more efficientperformance, it is preferably necessary to exclude a puncturing for aspecific sequence having higher importance among the convolutionallycoded output sequences.

Currently, it is desirable to exclude the puncturing for the sequence‘z’ outputted by “711₈=111001001₂” polynomial among the three outputsequences x,y,z coded convolutionally. Accordingly, in preferredembodiments of the present invention, the parameters of table 4 are usedso as to perform the puncturing only for the sequence ‘x’ outputted by“557₈=101101111₂” polynomial. In another inventive example, theparameters of Table 5 are used so as to execute alternately thepunctures for the sequence ‘x’ outputted by “557₈=101101111₂” polynomialand the sequence ‘y’ outputted by “663₈=110110011₂” polynomial.

Parameters shown in the tables 6 and 7 can be used selectively accordingto the present invention when the channel encoder performs theconvolutional coding.

TABLE 6 557₈ 663₈ 711₈ sequence (x) sequence (y) sequence (z) a 2 2 1number of puncturing P 0 0 bits sequence length └N_(c)/3┘ └N_(c)/3┘└N_(c)/3┘

TABLE 7 557₈ 663₈ 711₈ sequence (x) sequence (y) sequence (z) a 2 2 1number of puncturing ┌P/2┐ └P/2┘ 0 bits sequence length └N_(c)/3┘└N_(c)/3┘ └N_(c)/3┘Thus, the same rate matching puncturing algorithm can be used in theuplink and downlink by controlling and using the parameters in thepreferred embodiments of the inventive rate matching puncturingprocedure. Further, the same rate matching puncturing algorithm can beused for the turbo and convolutional code. In particular, a specificlogic is not needed for excluding of the puncturing when applying theparameters above.

As described above, the preferred embodiment of a method of constructingthe parameters was described to gain the uniform puncturing pattern inthe uplink. In the above procedure, the puncturing for the overall bitcolumn operates until 33.3% without any difficulty. If a puncturing over33.3% occurs such as when the target coding rate to be obtained throughthe rate matching puncturing is more than ½, the puncturing for eachparity sequence is generated over 50% respectively. A mean puncturingdistance q based on the code symbol unit for each parity sequence isgotten by “q=└N/|N_(i)−N|┘”, and thus a value less than 2 is obtained.

As described hereafter, ΔN is defined as the amount of rate matching. Ifthe number of input bit to the rate matching block is N and ΔN amount ofrate matching is performed in the rate matching block, the resultantoutput from RMB has a length of N+ΔN. In the above, N_(i) can berepresented as N+ΔN. Therefore, if ΔN has a negative sign, then it means|ΔN| amount of puncturing should be imposed in the RMB. Otherwise, ΔNamount of repetition should be imposed in the RMB. Accordingly, ΔN isnow a signed value.

When q has a value less than 2, it is determined in the related art thatthe shifting parameter value for each radio frame alternately has 0and 1. Further, in the base process of the preferred embodiments, thepuncturing operates well only in a case that a ratio between N and |ΔN|is near 2. The smaller its ratio is from 2, the less the uniformity ofthe puncturing patterns becomes. That is, though the uniform puncturingfor each column is generated, the uniform puncturing condition for thesequence before virtual interleaving is not satisfied.

In an inventive example according to the preferred embodiments, when thepuncturing rate for an overall bit column is over 33.3% in the ratematching procedure, namely, in case that the puncturing over 50% eachinfluences upon two parity sequences, the shifting value is calculatedby exchanging a concept for a bit position having a generation of thepuncturing and a bit position not having a generation of the puncturingto gain more uniform puncturing pattern. In particular, the number ofbits not having a generation of the puncturing is applied to acalculation of the shifting parameters.

In preferred embodiments when puncturing over 50% should influence uponeach parity sequence, a new parameter R is defined by a modified modulooperation so that more uniform puncturing may be generated, and a rangeof the puncturing is preferably computed by using this parameter R.Here, modulo operation on negative value is defined in a circularmanner, which means, ΔN mod N≡N−|ΔN|, if ΔN is negative.

According to the present invention, in cases that the puncturing over50% is generated and the puncturing under 500% is generated,respectively, for two parity sequences, each parameter q that representsa mean puncturing distance of the code symbol unit is computeddifferently from each other. Finally, the shifting parameters arecalculated by the mutual differently computed ‘q’ according to thepuncturing rate and it is used for the rate matching puncturingalgorithm.

In the above generalized rate matching algorithm, the parameter qindicating the average puncturing distance of the code symbol unit q hasa positive (+) value in case that the puncturing over 50% each for thefirst and second parity sequences is performed. Meantime, q has anegative (−) value in case the puncturing each under 50% for two paritysequences. Thereby, it is used to compute the shifting parameters foreach parity sequence.

Another parameter determination process of the preferred embodimentsaccording to the present invention for computing the shifting parametersfor the 1st parity sequence provided at this time will now be described.

“N=└N_(C)/3┘; each sequence size for puncturing.

ΔN_(i)=└ΔN/2┘; bit quantity to be punctured for 1st parity sequencewhere |ΔN| means the amount of puncturing for each column in 1stinterleaver.

“R = ΔN_(i) mod N = N − |ΔN_(i)|;  ; if((R ≠ 0)&(2*R≦N)) q = ┌N / R┐else q = ┌N / (R − N)┐ endif if q is even${{then}\mspace{14mu} q^{\prime}} = {q + \frac{{GCD}\;\left( {{q},K} \right)}{K}}$else q′ = q endif for(i=0;i<K;i++) k = |└i* q′┘| mod K S₁[R[(3k + 1) modK]] = |└i* q′┘|divK endfor”

A similar procedure is preferably applied to the 2nd parity sequence tocalculate the shifting parameter S₂ for 2nd parity sequence.

N=└N_(C)/3┘; each sequence size for puncturing

ΔN_(i)=┌ΔN/2┐; bit quantity to be punctured for 2nd parity sequencewhere |ΔN| means the amount of puncturing for each column in the 1stinterleaver.

“R = ΔN_(i) mod N = N − |ΔN_(i)|; if((R ≠ 0)&(2*R≦N)) q = ┌N / R┐ else q= ┌N / (R − N)┐ endif if q is even${{then}\mspace{14mu} q^{\prime}} = {q + \frac{{GCD}\;\left( {{q},K} \right)}{K}}$else q′ = q endif for(i=0;i<K;i++) k = |└i* q′┘| mod K S₂[R[(3k + 2) modK]] = |└i* q′┘|divK endfor”

In two parameter determination algorithms above,

$``{q^{\prime} = {q + \frac{{GCD}\left( {{q},K} \right)}{K}}}"$is provided to prevent the puncturing from being continued in the samecolumn, and “k=|└i*q′┘|mod K” indicates a column number on the virtualinterleaver. Also, “S₁[R[(3k+1)mod K]]=|└i*q′┘|divK” is the expressionshowing the procedure of conceptualizing the shifting parameter per eachcolumn of the virtual interleaver for the first parity sequence in dueorder of actual radio frames, and “S₂[R[(3k+2) mod K]]=|└i*q′┘|divK” isthe expression representing the procedure of conceptualizing theshifting parameter per each column of the virtual interleaver for thesecond parity sequence in due order of actual radio frames.

In the above-described procedure, “if ((R≠0)&(2*R≦N))” corresponds to acase of the puncturing rate over 50%. That is, considering the case thepuncturing occurs over 50%, it is calculated by “R=N−|ΔN_(i)|” asdescribed above. Consequently, when the q value is computed by using theR value, it can be noted that the number of bits not having anoccurrence of the puncturing is represented among a length of an overallbit column for virtual interleaver, N, inputted to the rate matchingblock. In an opposite case, since “R−N=−|ΔN_(i)|” is used in thecalculation of the q value, it can be noted that the q value is computedby the actual puncturing number in result.

By using the above procedure for calculating the average puncturingdistance q of the code symbol unit for each parity sequence, theabsolute value of q always has a larger value than 2. Therefore, auniformity of the puncturing pattern is maintained according to thepreferred embodiments.

For example, assuming that the overall bit column to be rate-matched isconstructed by 24 bits, namely, N_(C)=24, and ΔN is −12 by a generationof 50% puncturing for the overall bit column, 6 bits among the firstparity sequence constructed by eight bits are punctured, namely thepuncturing over 50% is generated. Equally, 6 bits are punctured even forthe second parity sequence. In this case, in the parameter determinationalgorithm for calculating the inventive shifting parameter, it iscalculated by the parameter R=N−|ΔN|=8−6=2. Since “R=2” satisfies thecondition of “(R≠0)&(2*R≦N)”, the average puncturing distance q of thecode symbol unit for the 1st parity sequence becomes “┌8/2┐=4”. In otherwords, in gaining the average puncturing distance, a bit number notpunctured, as 2, is used instead of 6 as a bit number to be punctured.It can be noted that the shifting is performed on the basis of bits nothaving an occurrence of the puncturing in calculating the shiftingvalues.

FIG. 14 a shows the puncturing pattern on the virtual interleaver forthe first parity sequence of the turbo code using the existing shiftingparameter computing method. In FIG. 14 a, assume that the overall bitcolumn to be rate-matched is constructed by 24 bits, namely, N_(C)=24,and ΔN is −12 by a generation of 50% puncturing for this overall bitcolumn. As shown in FIG. 14 a, a position not having a generation of thepuncturing occurs concentratedly on third and fourth rows and on seventhand eighth rows of the virtual interleaver.

FIG. 14 b represents the puncturing pattern according to the preferredembodiments on the virtual interleaver for the 1st parity sequence,which is obtained by using the shifting parameter computing methodmodified for such a case. As shown in FIG. 14 b, a position not having ageneration of the puncturing becomes uniform as possible.

Finally, even though the puncturing over 50% occurs for the each paritysequence, according to preferred embodiments of the present invention,it can be noted that the absolute value of the average puncturingdistance q based on the code symbol unit for each parity sequence alwayshas a larger value than 2. If a quantity of the puncturing for eachparity sequence becomes below 50%, the shifting value gained by theabove-described method and the shifting value gotten by the existingmethod mutually coincide. The puncturing pattern on the virtualinterleaver of each parity sequence can also gain that same uniformpuncturing pattern.

A repetition procedure for the channel code of the uplink will now bedescribed in another preferred embodiment according to the presentinvention. In the preferred embodiments of the rate matching proceduresdescribed above, K used in the parameter determination algorithm isdetermined as one out of values as 1, 2, 4 and 8. Also, q′ is not aninteger but a multiple of ⅛. The q is a medium parameter for getting theshifting parameter and indicates a mean repetition distance on theoverall bit sequence.

In the preferred embodiments of the inventive repetition procedure,further, the shifting parameter per each column is determined by theparameter determination process, after that, a repetition procedure ispreferably performed. Different from the puncturing procedure mentionedabove, there is no need of performing the separate rate matchingrepetition to the branched-off coded bit stream. That is the ratematching repetition is performed over the coded bit stream that is notbranched off.

The existing parameter determination algorithm is more based on theshifting parameter calculation provided for the sake of the puncturingprocedure. Thus, if the existing parameter determination algorithm isapplied to the repetition procedure as it is, various problems arecaused. For example, a repetition rate considerable for each sequenceinputted for a repetition procedure is currently more than 100%.Actually different from the puncturing procedure, there is no explicitupper limit to repetition ratio. When applying the current repetitionprocedure as it is, some problems occur when the repetition rate exceeds50%. When the repetition rate is over 50%, in which a first problem iscaused in case that the repetition rate exceeds 100%, and a secondproblem is caused when the repetition rate is near to 50% together withexceeding 50%.

First, a case where the repetition rate exceeds 100% for each inputtedsequence is when the bit number repeated per each column, ΔN, is largerthan an input sequence size N. In this case, the q value is determinedas ‘0’, and therefore, the shifting parameter for the rest other columnsexcepting of a first column of the 1st interleaver is not allotted. Thatis, the shifting parameter computation per each column of the 1stinterleaver is impossible.

Second, the existing parameter was decided by considering only a casethat the repetition rate for the inputted sequences is under 0˜50%, anda case of a repetition rate exceeding 50% was not considered.

Accordingly, a repetition pattern as shown in FIG. 15 a can occur. FIG.15 a depicts the repetition pattern provided by using the basicparameter. If the parameter proper to the repetition rate of 51% iscalculated by the parameter determination algorithm of computing theshifting parameter provided for the repetition procedure, the averagerepetition distance of the code symbol unit, q, has a smaller value than2, as known in “q=└N/|ΔN|┘=└100/51┘”. Finally, “q=1” is applied in theactual algorithm, thereby the shifting parameters for all columns of the1st interleaver are calculated as 0.

In a case of N=11, ΔN=6 and K=8, q becomes 1. Therefore, a finallycomputed shifting parameter becomes 0 and so the repetition pattern isrepresented as shown in FIG. 15 a. That is, when it is the repetitionrate over 50%, there occur cases that all bits are repeated on some rowsand bits are never repeated on some rows, which destroys the uniformityrequirements in the sequence before 1st interleaving.

In preferred embodiments according to the present invention for suchcases, three methods for settling problems caused in the existed casethat the repetition rate exceeds 50% will now be described.

A first method is the following shifting parameter computation procedureprovided by considering when the repetition rate is near to 50% togetherwith exceeding 50%. The shifting parameter to be applicable to each 1stinterleaver memory column is preferably calculated for sequence inputtedto the 1st interleaver, as follows.

“ q = └N/ΔN┘ if(q<=2)  for l=0 to K−1    S[R[l mod K]]=(l mod 2) else ifq is even  then q′ = q − GCD(q,K)/K else  q′ = q endif for k=0 to K−1   S[R[┌k* q┐mod K]]= ┌k* q′┐divK end-for ”

In such a case that the q value indicating the average repetitiondistance of the code symbol unit is computed as a value smaller than 2,the shifting parameter allotted per each column is determined as 0 and 1alternately. In an example, when the input sequence size N is 11, andrepeated bit numbers for the input sequence are determined as ΔN=6 andK=8, the shifting parameter of 0 or 1 per each column is actuallyapplied to the repetition algorithm. Finally, when the repetition rateis approximate to 50% together with exceeding 50%, positions of bitsrepeated as shown in FIG. 15 b have a uniform repetition pattern on therest rows excepting of a first row.

However, when the repetition rate is under 50%, the shifting parameterper each column of the virtual interleaver is calculated by “S[R[┌k*q┐mod K]]=┌k*q′┘ divK” similar to the existing method, and after that, theuplink repetition algorithm is performed by using the decided parametervalue.

In a second method for a case that the repetition rate for the inputsequence exceeds 100%, a shifting parameter computation procedure isprovided by considering when the bit number ΔN repeated per each columnis larger than the input sequence size N. The shifting parameter to beapplied to each 1st interleaver memory column is calculated for sequenceof the 1st interleaver, as follows. At this time, a parameter R isdefined using the modulo operation, and R is used in computing a mediumparameter q representing the average repetition distance overall thecoded bit stream.

“ R = |ΔN| mod N  q = └N/R┘ ------- only if R ≠ 0 if q is even  then q′= q − GCD(q,K)/K else    q′ = q endif for k=0 to K−1    S[R[┌k* q┐modK]]= ┌k* q′┐divK end-for ”

When in the above the input sequence size N is 11 and a repeated bitnumber ΔN for the input sequence is 13, for example, R is calculated as2 by “R=ΔN mod N”. According to that, q is computed as 5 by “q=└N/R┘”,differently from the existed case that q is calculated as 0.

This value is applied to “S[R[┌k*q┐ mod K]]=┌k*q′┐ divK” to calculatethe shifting parameter per each column of the 1st interleaver, and theuplink repetition algorithm is performed by using such decided parametervalue. Finally, in case the repetition rate exceeds 100%, 100%repetition is executed for the inputted sequence. Then, a new q valuefor deciding the rest bit positions to be repeated is computed.According to that, positions of the rest repeated bits have a uniformrepetition pattern by applying the shifting parameter value to theuplink repetition algorithm.

A third method is preferably provided by combining the above first andsecond methods. The third method combines the parameter determinationprocedures for a computation of two shifting parameters, which isapplied to the cases that the repetition rate is near to 500% togetherwith exceeding 50% and a bit number ΔN repeated per each column islarger than the input sequence size N.

The shifting parameter to be applied to each 1st interleaver memorycolumn is calculated as follows for sequence inputted to the 1stinterleaver. At this time, also, a parameter R is used in computing amedium parameter q representing the average repetition distance of thecode symbol unit. In the following procedure, it can be applied even toa case of ‘R=0’. Namely, a case that the repetition rate is 100% or200%.

  “ R = ΔN mod N   if(R=0) q=1;   else q = └N/ΔN┘ endif   if(q<=2)   for l=0 to K−1      S[R[l mod K]] = l mod 2   else    if q is even   then q′ = q − GCD(q,K)/K    else      q′ = q   endif   for k=0 to K−1        S[R[┌k* q┐mod K]]= ┌k* q′┐divK   end-for ”

The above algorithm is all applicable when the repetition rate is morethan 100% available for the current input sequence. If the shiftingparameter decided according to that is applied to the uplink repetitionalgorithm, the repetition pattern in which positions of repeated bitsare completely uniform can be obtained.

As described above, the preferred embodiments according to presentinvention provide various advantages. First, a puncturing having apuncturing distance based on a uniform symbol unit for each paritysequence of RSC coders among puncturing conditions for a turbo code inan uplink can be obtained. Second, a uniform puncturing is embodied evenin the uplink to remarkably increase an overall decoding performance,since the puncturing distance of the symbol unit can be designated,using the puncturing algorithm based on the existing bit unit as it is.Third, the uniform puncturing is satisfied regardless of a bit quantityto be punctured. Therefore, the same parameter can be applied theretoand used in the puncturing algorithm for a channel code of an uplink anda downlink.

In addition, when the puncturing for an overall input sequenceturbo-coded in the uplink is more than 33.3%, the uniform puncturingcondition is satisfied on each column and row of a virtual interleavingpattern. Thus, even in case that each puncturing rate is over 50% on 1stand 2nd parity sequences, the uniform puncturing condition is satisfiedon each column and row of a virtual interleaving pattern.

Better pattern performance is obtained in case that the puncturing ratefor the turbo-coded overall sequence is over 33.3%. Accordingly, itsoperation can be performed more smoothly for a limited upper range ofthe puncturing quantity not only in a normal mode but also in acompressed mode particularly.

According to the preferred embodiments, the shifting parameter per eachcolumn of a used interleaving pattern can be calculated even for anyrepetition rate. Especially, even in case that the repetition rate forthe input sequence exceeds 100% and a bit number repeated per eachcolumn is larger than an input sequence size, each shifting parameter isagain computed, for the rest other columns containing a first column ofthe interleaving pattern. Accordingly, a uniform repetition pattern canbe gained by applying this shifting parameter to an uplink repetitionalgorithm. Further, in case the repetition rate for the input sequenceis near to 50% together with exceeding 50%, the shifting parameter to beapplied to the uplink repetition algorithm is computed by using aspecifically added function(R). Thereby, a uniform repetition patterncan be obtained on remaining rows excepting of a first row according toa characteristic of the repetition algorithm.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

1. A rate matching method for uplink of a mobile communication system,the method comprising: interleaving turbo-coded bits which consist of afirst sequence, a second sequence and a third sequence output from aturbo encoder at an interleaver; determining a total number of bits tobe punctured or repeated (ΔN) for the turbo-coded bits, a first numberof bits to be punctured or repeated for the second sequence, a secondnumber of bits to be punctured or repeated for the third sequence, andan average puncturing or repetition distance (q), wherein the firstnumber and the second number are determined differently when (ΔN) is anodd number; determining a first shifting parameter for the secondsequence and a second shifting parameter for the third sequence, whereinthe first and second shifting parameters are determined differentlyaccording to a value of (q); and performing a rate matching for each ofthe second sequence and the third sequence by using the determined firstand second numbers and the determined the first and second shiftingparameters.
 2. The rate matching method according to claim 1, whereinthe first number is determined as a largest integer number not greaterthan (ΔN/2) and the second number is determined as a smallest integernumber not less than (ΔN/2).
 3. The rate matching method according toclaim 1, wherein (q) is determined differently for the second sequenceand the third sequence when (ΔN) is an odd number.
 4. The rate matchingmethod according to claim 1, wherein the first shifting parameter andthe second shifting parameter are determined independently.
 5. The ratematching method according to claim 1, wherein performing the ratematching comprises: performing the rate matching for the second sequenceby using the determined first number and the determined first shiftingparameter; and performing the rate matching for the third sequence byusing the determined second number and the determined second shiftingparameter.
 6. The rate matching method according to claim 1, furthercomprising: determining an initial error offset value (eini) for use inperforming the rate matching based on the determined first and secondshifting parameters and a predetermined constant (a), wherein (eini) isdetermined differently for the second sequence and the third sequencebased on the first and second shifting parameters.
 7. The rate matchingmethod according to claim 6, wherein (a) is predetermined differentlyfor the second sequence and the third sequence.
 8. The rate matchingmethod according to claim 6, wherein (a) is predetermined as 2 for thesecond sequence and (a) is predetermined as 1 for the third sequence. 9.The rate matching method according to claim 1, wherein both the firstand the second shifting parameters are determined differently accordingto whether (q) is greater than 2 and a modified average puncturing orrepetition distance value (q′) is used to determine the first and thesecond shifting parameters when (q) is an even number greater than 2.10. The rate matching method according to claim 9, wherein (q′) iscalculated by subtracting a variable from (q), the variable determinedbased on a relation between (q) and a number of columns of interleavedturbo-coded bits (K).
 11. The rate matching method according to claim 9,wherein (q′) is defined as [(q)−gcd (q, K)/K], wherein (K) is a numberof columns of interleaved turbo-coded bits and “gcd (q, K)” indicates agreatest common divisor of (q) and (K).
 12. The rate matching methodaccording to claim 1, wherein (ΔN), the first number, the second number,(q), the first shifting parameter and the second shifting parameter aredetermined by a rate matching module and the rate matching is performedby the rate matching module.
 13. The rate matching method according toclaim 1, wherein the first sequence corresponds to a systematic sequenceof the turbo-coded bits, the second sequence corresponds to a firstparity sequence of the turbo-coded bits and the third sequencecorresponds to a second parity sequence of the turbo-coded bits.